In common installations of reciprocating slat conveyors the truck or trailer comprises two parallel chassis beams on which are supported a plurality of cross beams, perpendicular to the chassis beams and spaced evenly along them. The conveyor mechanism itself is mounted on the cross beams and comprises a plurality of longitudinal beams, parallel to the two chassis beams, a plurality of bearing strips installed on the longitudinal beams and a plurality of slats which extend longitudinally and are slidably carded on the bearing strips. The slats are divided into groups of equal numbers, usually three groups. In basic operation, when all groups are moved in one direction the cargo moves with them. When the groups are moved in the opposite direction one at a time, the cargo does not move.
There are common, chronic problems with reciprocating slat conveyors as briefly described above. One problem is that particulate matter infiltrates the mechanism during the jolting and jostling when the conveyance is under way and also while the conveyor is operating. A second and somewhat related problem is that when the vehicle carrying the conveyor is underway and not loaded, the slats rattle against their supports and each other and suffer wear and cause unwelcome noise. The infiltration can accumulate and “freeze” the mechanism, rendering it inoperative and difficult to repair.
Several techniques are or have been used in efforts to alleviate or solve these problems. One example is disclosed in U.S. Pat. No. 4,144,963, issued to Olaf A. Hallstrom in 1979. In Hallstrom, conveyor the slats are mechanically firmly limited in vertical displacement relative to their supports and there are seals running longitudinally between the slats. This arrangement was found to be unsatisfactory and concepts not using seals, as such, were conceived, patented and used. U.S. Pat. No. 5,560,472, issued to Richard T. Gist in 1996 discloses a conveyor which is characterized as sealless and in which there are portions of the slats which are called seal beads. The seal beads contact the bearing strips and carry the weight of the slats and cargo supported by the slats, functioning as bearings and sealing incidentally. There were enough problems with the Gist concept to warrant further development, some of which is disclosed in U.S. Pat. No. 5,850,905, issued in 1998 to Raymond Keith Foster. Foster had acquired the rights to the Gist '472 patent and features resembling some of Gist features are incorporated in some of the variety of embodiments disclosed in the Foster '905 patent. There are features in Foster's '905 patent which are particularly important prior art to the subject patent. In most of the embodiments the seat beads of the slats are free to move away from the bearing strips up to one eighth inch. The purpose of this is stated to be to allow particulate matter trapped on the bearing strips to fall between the seal beads and the bearing strips to the ground below. However, an embodiment shown in FIG. 8 of the Foster '905 patent has bearing strips configured so that the seal beads are “urged into bearing seal contact with the bearing surfaces”. This feature provides longitudinal cavities into which particles can travel and be trapped. This type of bearing strip is numbered 80″ in FIG. 8 of the Foster '905 patent. In other embodiments disclosed in the Foster '905 patent, the bearing strips 80, 80′ and 98 have edges which extend laterally on each of their sides beyond the edges of the bearing strips and are notched along their edges to provide more space for particulate matter which escapes through the bearing seal contacts to fall to the ground. These bearing strips extend the full length of the conveyor and the notches are machined since they cannot be extruded or economically molded. There is no written or pictorial evidence in the Foster disclosure that the bearing strips in the embodiment shown in FIG. 8 have notches in the edges of the bearing strips anywhere long their lengths.
A universal feature of many of the prior art reciprocating conveyors, is that the bearing strips and slats must be installed longitudinally. This is known to be a cumbersome and often difficult procedure, and space consuming, especially considering the 40 to 50 foot length beds of some trucks and trailers. It is well known that there is voluminous prior art in the field of the subject invention and that cited is considered to be the most pertinent currently known. In view of the above discussion the primary objective of the subject invention is to provide a sealless reciprocating slat conveyor which has minimum chance of becoming jammed and incapacitated by unwanted accumulations of particulate matter. A second objective is that the slats and bearing components be installable vertically, i.e. from above the slat and bearing support structure.
The following additional United States patents should be considered when putting the present invention into proper perspective relative to the prior art:
U.S. Pat. No. 4,679,686, issued Jul. 14, 1987 to Raymond Keith Foster; U.S. Pat. No. 4,858,748, issued Aug. 22, 1989 to Raymond Keith Foster; U.S. Pat. No. 5,044,870, issued Sep. 3, 1991 to Raymond Keith Foster; U.S. Pat. No. 5,096,356, issued Mar. 17, 1992 to Raymond Keith Foster; U.S. Pat. No. 5,238,360 issued Aug. 24, 1993 to Raymond Keith Foster; U.S. Pat. No. 5,355,996, issued Oct. 19, 1994 to Raymond Keith Foster; U.S. Pat. No. 5,415,271, issued May 16, 1995 to Raymond Keith Foster; U.S. Pat. No. 5,419,426, issued May 30, 1995, to Raymond Keith Foster; U.S. Pat. No. 5,433,312, issued Jul. 18, 1995 to Raymond Keith Foster; U.S. Pat. No. 5,547,067, issued Aug. 20, 1996 to Raymond Keith Foster; U.S. Pat. No. 5,560,472, issued Oct. 1, 1996 to Raymond Keith Foster; U.S. Pat. No. 5,605,221, issued Feb. 25, 1997 to Raymond Keith Foster; U.S. Pat. No. 5,806,660, issued Sep. 15, 1998 to Raymond Keith Foster; U.S. Pat. No. 5,850,905, issued Dec. 22, 1998 to Raymond Keith Foster; U.S. Pat. No. 5,860,507, issued Jan. 19, 1999 to Raymond Keith Foster; U.S. Pat. No. 5,996,772, issued Dec. 7, 1999 to Raymond Keith Foster; U.S. Pat. No. 6,013,585, issued Jan. 11, 2000 to Raymond Keith Foster and James Bradley Fete; and U.S. Pat. No. 6,019,215, issued Feb. 1, 2000 to Raymond Keith Foster.
Foster '748 discloses bearing members which are adapted to be snap-fitted onto longitudinal bearing support beams and conveyor slats that are adapted to be snap-fitted onto the bearings. Foster '360 discloses another bearing construction that is adapted to be snapped onto support beams for the bearings and conveyor slat members that are adapted to be snapped onto the bearings.